1. Field of the Invention
The present invention relates to a surface acoustic wave device and to a manufacturing method for the surface acoustic wave device, and more specifically relates to a surface acoustic wave device including a closed space and to a manufacturing method for the surface acoustic wave device.
2. Description of the Related Art
To date, a variety of surface acoustic wave devices having a closed space have been provided.
For example, in a surface acoustic wave device 101 illustrated as a sectional view in FIG. 15, a piezoelectric substrate 103 and a cover 137 are bonded to each other with a frame-shaped support layer 135 interposed therebetween and a closed space 110A is formed between the piezoelectric substrate 103 and the cover 137. A conductor pattern 111A that includes IDT electrodes and reflectors of surface acoustic wave elements and pads and wiring lines is formed on a main surface of the piezoelectric substrate 103 that faces the cover 137. A through conductor 107A that penetrates through the support layer 135 and the cover 137 and is electrically connected to a pad 113A is formed of a base layer 139 that is deposited on a bottom surface and an inner peripheral surface of a hole 105h through the support layer 135 and the cover 137 and around the hole 105h on the upper surface of the cover 137, and a solid portion 141 that fills the inside of the base layer 139 (for example, refer to Japanese Unexamined Patent Application Publication No. 2011-172190).
Surface acoustic wave devices can be efficiently manufactured by processing a plurality of such devices all together on a wafer piezoelectric substrate (aggregate substrate) and then dividing the substrate into individual substrates. When through conductors are to be formed by performing electroplating in the aggregate substrate state, a feed line is formed in advance on the aggregate substrate so that a current may flow to the pads in the plating step. The feed line is cut when the aggregate substrate is divided into individual substrates. Consequently, the feed line extends to an outer peripheral edge of a main surface of the piezoelectric substrate in each device divided from the aggregate substrate.
When the aggregate substrate is cut and divided into individual substrates by dicing, the feed line may peel off from the main surface of the piezoelectric substrate during dicing, adhesion between the support layer and the piezoelectric substrate, which form the closed space, may be reduced and a sealing property of the closed space may be reduced.